1. Field of the Art
This invention relates generally to nose bag applicators for wrapping a balloon or a bag-shaped fluid-tight covering case of elastic membranous material on a nose end of rod-like insertion type internal examination instrument such as ultrasound probes, ultrasound scanners and ultrasound endoscopes, and more particularly to a nose bag applicator with a pinhole checker for testing fluid tightness of a balloon or bag-shaped elastic covering case to be put on a nose end of an insertion type internal examination instrument immediately before use.
2. Description of the Prior Art
For instance, insertion type ultrasound examination instruments such as ultrasound probes, ultrasound scanners and ultrasound endoscopes generally have an ultrasound transducer member mounted at a nose end of a flexible insertion rod to be introduced into an intracavitary portion of particular interest. Normally, a bag-shaped balloon is fitted on a nose end of the insertion rod in such a manner as to hermetically enclose a tip end section which supports an ultrasound transducer or transducers. Prior to an ultrasound examination, the balloon is filled and inflated with deaerated water or a suitable ultrasound transmission medium thereby to suppress attenuation of ultrasound signals and at the same time to secure a suitable standoff margin for the ultrasound transducer. Moreover, for the purpose of wrapping a balloon tightly on the insertion rod free of positional deviations in the course of insertion into an intracavitary region of examination, balloons of this sort are normally designed to have a diameter and a length which are, in a free deflated state, appreciably smaller than an outside diameter and an axial length of a nose end portion of an insertion rod, so that they more or less need to be stretched into a tensioned state when fitting on a nose end of an insertion rod. Accordingly, while in a deflated state before charging deaerated water or the other ultrasound transmissive medium, the balloon necessarily fits tightly on the surfaces around the circumference of the ultrasound insertion rod. Because of the tightness of a balloon in a fitted state and because of the necessity for fitting a fresh balloon on an insertion rod prior to each ultrasound examination, it is usually the case that the operator is required to undergo great efforts in a preparatory stage of an ultrasound examination for manually putting on a balloon on a nose end of an insertion rod to be used.
In an attempt to overcome the difficulties as mentioned above, there have been developed and introduced into use the so-called nose bag applicators which permit to put on balloons in a facilitated manner, for example, a piston and cylinder type nose bag applicator as proposed in Japanese Utility Model Publication H6-32081. In the case of the nose bag applicator of the publication just mentioned, a piston member is slidably fitted in a hollow cylindrical body which has an inside diameter larger than an outside diameter of a nose end of an ultrasound insertion rod to be used. A manual operating means is connected to the piston member to operate the same in directions inward and outward of the cylindrical body. An open end of a balloon, which is generally in the shape of a bag or sack, is hermetically fitted on a distal fore end portion of the cylindrical body in such a way as to form a closed space between the piston member and the balloon, so that, if the piston is pulled outward or toward the proximal end of the cylindrical body to expand the volume of the closed space, the balloon is sucked in and spread in a reversed state against the inner periphery of the cylindrical body under the influence of a negative pressure which is developed by the rearward expanding movement of the piston. In this state, a nose end portion of an ultrasound insertion rod is put into the cylindrical body which holds the balloon against its inner periphery, and then the open end portion of the balloon is detached from the fore distal end of the cylindrical body, letting the balloon fit tightly on the nose end portion of the insertion rod in an extremely facilitated manner.
At the time of wrapping a balloon on a nose end of an insertion rod in a preparatory stage of an ultrasound examination in the above-described manner, the balloon which is formed of a thin film-like membranous material might contain a pinhole or a similar defect which is detrimental to hermetical tightness of the balloon. Of course, all of balloons of this sort are usually tested for hermetic tightness before shipping, but there are still the possibilities of the balloons picking up pinholes or other defects while being handled after shipping, let alone the minute pinholes which have been overlooked in a quality check. Should a balloon wrapped on an ultrasound insertion rod contain a pinhole, it is very likely that liquid leaks through the pinhole occur upon pumping deaerated water or another ultrasound transmissive medium into the balloon after insertion into an intracavitary region to be examined. Taking into account the fact that an ultrasound transmissive medium is normally fed under a relatively high pressure, it could enlarge the pinhole to magnify the extent of liquid leaks, resulting in total deflation of the balloon especially in case of an examination which extends over a relatively long time.
Moreover, in some cases a covering case of rubber or other elastic membranous material is fitted on an ultrasound insertion rod for the purpose of preventing contamination of the rod. In such a case, the covering case should also be able to maintain hermetic tightness since otherwise the surfaces of the insertion rod would be contaminated with intruding body fluids. However, as a matter of fact it has been difficult to spot minute defects like pinholes in a covering case simply by visual observation at the time of wrapping it on an insertion rod, despite dangerous situations which can result, such as proliferation of germs in unknowingly contaminated areas of an insertion rod. Therefore, from a hygienic point of view. It is desirable also for such covering cases to be tested for fluid tightness by a pinhole check immediately before use.